Old Reservoir
Randolph County, Missouri21 acresView mapDirections
Nutrients and algae sit mid-range for this region.
- Eutrophic
- #2 of 7 in the county
- Public access
Old Reservoir in Randolph County, Missouri has a water quality grade of C (Fair). Water clarity: 3.6 ft visibility. Phosphorus: 33 µg/L. Chlorophyll-a (algae): 14.2 µg/L. Surface area: 21 acres.
- Clarity
- 3.6 ft
- Typical in September
- 74°F
- Area
- 21 acres
- Type
- Eutrophic
- Trend
- ↑ Improving
- Public access
- Yes
Stays via Stay22
Stays near Old Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Old Reservoir in Randolph County, Missouri — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Old Reservoir
Prices for Sep 11–13, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Missouri’s top lakes →
Watch Old Reservoir’s letter
Email me if this lake’s grade moves. Grades stay free.
Or email
Old Reservoir is a 21-acre productive, nutrient-rich eutrophic lake in Randolph County, Missouri. Water quality is graded C based on 2 sampling years through 2024. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 6 other monitored lakes in Randolph County, Old Reservoir ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2024-09-17. Grade methodology: LakeQuality methodology.
What Old Reservoir is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming Safety
Grade onlyModerate
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Murky, only visible to about 3.6 ft. Phosphorus 33 µg/L. Chlorophyll-a 14.2 µg/L. TSI 57. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.6 ft | Not graded |
| Phosphorus | 33 µg/L | Good |
| Chlorophyll-a (Algae) | 14.2 µg/L | Fair |
| Trophic State Index (TSI) | 57 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Temperature
Old Reservoir typically sits around 74°F at the surface in September. Summer average is about 80°F. Usually warmest in Jul (about 82°F) and coldest in Apr (about 59°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 98 field readings (2010–2024) via the EPA Water Quality Portal. See the full Old Reservoir water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 21 acres |
| Public Access | Yes |
No bathymetric survey has been published for Old Reservoir, so its depth is not documented here.
Recreation & Access
- Water Works Lake (Moberly)Public
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Old Reservoir
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.226 m/yr | 5 |
| Phosphorus | ↑ Improving | -4.33 µg/L/yr | 5 |
| Chlorophyll-a | ↑ Improving | -3.81 µg/L/yr | 5 |
Reservoir Info (USACE NID)
Old Reservoir is a man-made reservoir impounded by the Water Works Lake Dam (completed 1870), built primarily for recreation on the TRIBUTARY TO SWEET SPRING CRK; earth-type dam, 30 ft tall.
- Surface area
- 21 ac
- Normal storage
- 147 ac-ft
- Max storage
- 337 ac-ft
- Drainage area
- 418 sq mi
- Hazard class
- High
- Owner
- MOBERLY-PARKS&RECREATION
All listed purposes: Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID MO10006 · Operator website · Matched by proximity (0.04 km)
Regulated Pollution Sources Nearby
4 EPA-permitted facilities operate within about 5 miles of Old Reservoir under Clean Water Act (NPDES) discharge permits. 4 facilities have a reported Clean Water Act violation in the past three years.
- Fox Hollow Wastewater Treatment FacilityMoberly · 1.2 mi away · NPDES MO0035599Recent violation
- Orton Lane WwtfMoberly · 1.7 mi away · NPDES MO0121622Recent violation
- Heritage Hills Golf Course WwtfMoberly · 2 mi away · NPDES MO0095605Recent violation
- Moberly Mo Llc WwtfMoberly · 3.1 mi away · NPDES MO0045021Recent violation
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
County Ranking
Ranked #2 of 7 lakes in Randolph County
Nearby Lakes in Randolph County
Frequently asked questions about Old Reservoir
Where is Old Reservoir?
- Old Reservoir is a lake in Randolph County, Missouri. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Old Reservoir?
- Old Reservoir in Randolph County, Missouri has a water quality grade of C (Fair). Water clarity: 3.6 ft visibility. Phosphorus: 33 µg/L. Chlorophyll-a (algae): 14.2 µg/L. Surface area: 21 acres.
Is Old Reservoir safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Old Reservoir?
- Old Reservoir typically sits around 74°F at the surface in September, from 98 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
Are there boat ramps on Old Reservoir?
- Old Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Water Works Lake (Moberly). Public access is listed as yes.
Explore Old Reservoir across LakeQuality
More Missouri Lake Rankings
Other Grade C Lakes in Missouri
Eutrophic Lakes in Missouri
Where this data comes from
120 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Univ. of Missouri, Columbia
UMC120 samples · 2020–2024
Analytical methods
- Depth, Secchi disk in meters
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Named boat-access points from the USGS National Boat Ramps inventory